Electrical control system



P 1950 P. H. HOUSER ELECTRICAL CONTROL SYSTEM Filed Aug. 12, 1949 'Fhilip H. Housev;

iWfM IS Attorn ey Patented Apr. 25, 1950 T OFFICE ELECTRICAL CONTROL SYSTEM Philip H. Houser, Swampscott, Mass, assignor to General Electric Company, a corporation of New York 20 Claims.

This invention relates to electrical control systems, and more particularly to control systems for the operation of a relatively large number of lamps in series from a source of constant current, such as are used for street lighting, airports, and the like.

Such lighting systems generally are sectionalized, and the various groups of lamps to be lighted often cover a considerable area with at least some of the groups being remote from the control center. The conventional means for controlling such remote groups is to run control wires from the control center to short-circuiting switches located in these remote groups. Such control wires must carry sufficient current to operate these switches, and must be of sufiicient size to carry such current without prohibitive voltage drop. On very long runs, this means that the size of control wire needed becomes an important economic factor.

It is an object of this invention to provide a control system which permits the use of smaller control wires in such an installation. Broadly, the means to accomplish this end is provided by a control system in which the energy for operating the sectionalizing switches is taken from the series lighting circuit itself, thereby releasing the control circuit from the burden of carrying this energy.

This, and other objects not indicated above, will be apparent to those skilled in the art from a consideration of the following specification and nanying drawing, in which Fig. 1 is an electrical circuit diagram oi a preferred embodiment of my invention; Fig. 2 is an electrical circuit diagram of a modified embodiment thereof; while 3 illustrates a modification of shortcircuiting switch which is used in Figs. 1 and 2.

Referring to Fig. 1 of the drawing, there is shown a plurality of lamps It connected in series to source of substantially constant current 'such as the secondary winding of a constant current transformer ll. Transformer II is of a conventional type and may, for example, supply secondary current at an approximately constant va of 6.6 amperes to the lamp circuit. The pa ary winding of transformer H is connected to a suitable source of alternating current electrical energy (not shown) by means of switches and it which are operated in unison by a sole cl Solenoid it is energized from a suitable sou e of electrical control power which is represented by conductors l5 and 16, through a switch ll.

The lamps it! are separated into a plurality of banks Iii-23 inclusive. Six banks of lamps are shown in Fig. 1 for purposes of illustration, but it will be understood that a greater or smaller number of banks may be employed in. order to conform to the requirements of a particular installation, and further that the quantity of lamps making up each bank may be varied as desired. Each bank of lamps, except for the endmost bank 23, is separated into two sections which are connected in opposite sides of the series circuit. In a typical installation, each bank of lamps may be used to light a separate taxiway on an airport with the two sections of each bank being disposed on opposite sides of the taxiway, but it will be apparent that the invention is not limited to this type of installation.

series lamp circuit is separated into banks by means of a plurality of shunting, or short-circuiting switches 2t-28 inclusive, which, when closed, short-circuit the two sides of the series circuit. These switches are operated, respectively, by solenoids 29-33 inclusive. A plurality of transformers 34-31 inclusive, are provided which have their primary windings connected, respectively, in the lower sections of banks i'922. The secondaries of these transformers are connected, respectively, to solenoids 30-3 3. A plurality of switches 38- inclusive, which are operated, respectively, by an equal number of solenoids 42-45, are connected in shunt, respectively, with the secondaries of transformers Solenoid 29 and solenoids 42-45 are energized, respectively, by means of switches inclusive, which connect these solenoids to the source of control power through control conductors of suitable length.

In the operation of this system, control switch it is first closed to energize solenoid l4 and close switches i2 and l3. This energizes transformer H, which causes current to flow through the lamps in bank !8, thus causing the lamps in this bank to be lighted. Switch 24 is closed at this time, creating a short-circuit between the two sides of the series lamp circuit so that no current flows through banks of lamps l9--23 and, hence, the lamps in these banks are not illuminated.

When it is desired to illuminate bank I9, control switch 46 is closed, which energizes solenoid 2t and opens switch 24. This represents the conventional method of operating a short-circuiting switch in a constant current lighting system, in which the operating current for the switch is supplied by the source of control current. When the distance between the short-circuitin'g switch and the control center at which switch 46 is located is relatively short so that the connecting control conductors are short, this method is practical. The closing of switch 46 allows current to fiow through bank [9 and through the primary winding of transformer 34. The energizing of transformer 34 causes current to fiow from the secondary winding of the transformer through solenoid 30 to immediately close switch 25. This short-circuits the two sides of the series lamp circuit between banks l 9 and 20 and allows current to flow through the lamps in banks 18 and 89, thus lighting these two banks, but not thr ugh the remainder of the lamps.

When it is desired to illuminate the lamps in bank 20, control switch 4'! is closed, which energizes solenoid 42 and closes switch 33. This shortcircuits the secondary winding of transformer 34, thus deenergizing solenoid 3!! and causing it to drop out and open switch 25. This allows current to flow through bank 2!! and the primary winding of transformer 35. When transformer 35 is energized, the secondary current energizes solenoid 3|, which closes switch 26. This causes bank 20 and all banks to the left to be illum nated, while bank 21 and all those to the right remain dark. B nks 2|. 22 and 23 can be illuminated consecutively in the same manner as just described for bank 2!! by closing control switches 48, 49 and 50 in this order.

While similar symbols are used in the drawing for soleno ds 42-45 and for so enoids 29-33, it is im ortant to understand that the solenoids of the latter grou are physically much larger than those of the former roup. The switches ope ated lov solenoids 29-33 must switch under load the relatively high volta e of the series lamp circuit and, therefore, relatively large soleno ds must be used. In one typical installation embodying my invention, solenoids 29-33 are of a type which reouires approximately 9 amperes transient inru h current at 115 volts in order to operate the solenoids, while the steady current recu red to maintain them in the energized position after operation is ap roximately 3 am eres. The switches operated by solenoids 42-55 handle on y the secondary voltage of transformers E i-31 which is relatively low; therefore. these solenoids can be much smaller. For exam le, solenoids 42-45 ma have a tran ient inrush current of approximately .15 ampere and require approximately .045 ampere for continuous operation, both at 115 volts.

The above figures illustrate the advantage of my invention, in which energy for operating the short-c rcuiting switches between the various banks of lamps is taken from the series lamp circu t itself. over the conventional type system in which sufficient energy must be supplied through the control wires to o erate these switches. In a typical airport installation, for example, some or all of switches 25-28 inclusive, may be located at distances ranging up to several miles from the control center. If control currents of the order of several amperes were to be provided at such remote locations to operate switches 25-28, the conductors connecting control switches .1-! to the solenoids 30-33 which operate these switches would have to be large enough to carry the continuous operating current of the solenoids. Furthermore, on long runs, voltage drop becomes a major consideration and the control conductors would have to be large enough to prevent excessive voltage drop, particularly during the initial .period of high current when a solenoid is energized. Thus, the use of control solenoids 42-45,

which require relatively small operating currents, to provide for the operation of the main solenoids 30-33 from the series lighting circuit itself results in a considerable economic benefit.

It will be understood by those skilled in the art that it is possible to derive energy from the series lamp circuit for the operation of solenoids til-33 without the use of transformers B t-3f. For example, autotransformers may be substituted for the two winding transformers illustrated, or the coils of solenoids 33-33 may be connected directly in the series lamp circuit with switches 38-4! being used to shunt the solenoids to deenergize them. However, it is preferable to use two winding transformers, as shown, because the secondary voltage which is used to energize sole noids 38-33 may thus be made much lower than the potential of the lamp series circuit so that the secondary voltage can be handled by smaller switches, and, at the same time, the control circuts are insulated from the lamp circuit, thereby reducing the possibility of any feedback of high potential over the control wires.

It will be readily understood that with the arrangement illustrated in Fig. l, the various banks of lamps must be energized consecutively. That is, a bank of lamps cannot be illuminated unless all banks to the left of it in this figure are illuminated. In some installations, however, it is desirable to be able to illuminate the various banks of lamps at random and this may be ac comnlished by the use of a modificat on of my invention which is illustrated in Fig. 2 on the accompanying drawing.

In Fig. 2, like numerals represent like parts with Fig. 1. Only four banks of lamps are illustrated in Fig. 2, but it will be undertso-od that the invention is applicable to any number of banks. In this modification, the two sections of each bank of lamps are connected in series, respectively, to the two terminals of shunting switches 24-21. Thus. the current flows consecutively through all the lamps in each bank, w th the primary windings of transformers 34-35 being connected in the main series loop. either in the outgoing or ,return conductor rather than in the individual banks.

In order to illuminate the lamps in th s modified system, switch I! is closed to ener ize solenoid M which closes switches 82 and i3 and energizes constant current transformer l l in the same manner as in Fig. 1. As soon transformer H is energized, current starts to flow through the primaries of transformers 34-36. This energizes solenoids 30-32 which close switches 26-21, thus providing a holdin circuit for these solenoids, inasmuch as switch 24 is closed at this time. This means, therefore, that constant cur rent transformer II is energized and the system is in readiness for a selected one or more of the banks of lamps to be illuminated.

To illuminate one of the banks of lamps. the control switch corresponding to that bank is closed. For example, the closing of control switch 46 energizes solenoid 29 and opens shunting switch .24- which allows current to flow through the bank of lamps it. This represents the conventional method of operating a shortcircuiting switch in a constant current lighting system, in which the operating current for the switch is supplied by the source of control current. When the distance between the short-circutting switch and the control center at which switch 46 is located is relatively short so that the connecting control conductors are short, this accolades method is practical. If it is desired to. illuminate bank i9, control switch A! is closed, which ener gizes solenoid: 42 and closes. switch 38. This short-circuits the secondary of transformer 34, causing solenoid 30 to drop out and open. switch 25, which allows current to flow through bank l9. Banks 20 and 2| may be energized in the same manner as bank 19 by the operation of control switches 48 and 29, respectively. It will be readily understood that any one or more of the banks of lamps in Fig. 2 may be illuminated without the necessity of illuminating any of the other banks.

The modification illustrated in Fig. 2 requires extra conductors in the main series .circuit which are not required in Fig. 1, namely, the conductors which connect the primaries of trans formers 34-36 in the circuit between bank 2! and the secondary winding of transformer I l and the conductors connecting switches 2421.. However, such additional conductors are often justifiable economically in order to secure selectivity of operation of the various banks of lamps. The modification in Fig. 2 retains the advantage possessed by the system of Fig. l of requiring relatively small control conductors.

As an additional refinement, the single member shortcircuiting switches E i-48 in Figs. 1 and 2 may be replaced by a three member switch, as shown in Fig. 3. This switch is so arranged that when the solenoid is energized, contact member 5| closes its contacts before contact members 52 and 53 open theirs; similarly, when the solenoid is deenergized, contact members 52 and 53 close before contact member 5| opens. Thus it is possible to. avoid breaking the current in the main series loop. Instead, the series current is diverted through the lamps or the lamps are shunted, depending on whether the solenoid is deenergized or energized. The advantage of this type of switch is that all deenergized banks of lamps are disconnected completely from the main series circuit, and a ground fault in a bank of lamps may be isolated from the main series circuit by merely deenergizing the proper solenoid.

While I have shown solenoids exclusively as the operating means for the various switches included in the preferred. embodiment of my invention and in the modified embodiment thereof, it will be apparent to those skilled in the art. that other electrical operating means, such as motors, for example, may be substituted for the solenoid operating means without departing from the spirit of my invention. Other modifications may also be made by those skilled in the art. Therefore, it should be understood that. I intend to cover by the appended claims all modifications which fall within the true, spirit. and scope of my invention.

What I claim as new and desire to secure; by Letters Patent in the United States is :1

1. A control system for a plurality of lamps comprising a source of electrical energy providing substantially constant current, means. for connecting said lamps in a series circuit with said source, electrically operated means for shunting said series circuit at a plurality of locations relatively remote from said. source to separate said lamps into banks, and means for deriving. electrical energy from said series circuit at locations relatively remote from said source for the energization of said short-circuiting means.

2.. A control system for a plurality of lamps comprising a source of substantially constant current electrical energy, means for connecting said lamps in a series circuit with said source,

electrically operated short-circuiting means for separating said lamps into a plurality of banks, and. means for deriving electrical, energy from said series circuit for energizing said electrically operated means.

3'. A control system for a plurality of lamps comprising a source of electrical energy providing substantially constant current, means for connecting said lamps. in a. series circuit with said source, electrically operated means for shunting said series circuit at. a plurality of locations relatively remote from said source to separate said lamps into banks, means for deriving electrical energy from said series circuit at locations relatively remote from said source for the energization of said shunting means, and means for remotely controlling the energization of said shunting means.

i. A control system for a plurality of lamps comprising a source or? alternating current, a constant current transformer having its primary terminals connected to said source, circuit means for connecting said lamps in series to the secondary terminals of said constant current transformer, a plurality of short-circuiting switches for separating said lamps into banks, electrical operating means for said switches, a plurality of transformers having the primary windings connected in said series lamp circuit, the secondary windings of said transformers being connected to said electrical operating means, and shunting means for the secondary windings of said transformers.

5. A control system for a plurality of lamps comprising a soureof alternating current electrical energy, a constant current transformer having its primary winding connected tcsaid source, means for connecting said lamps in series to the secondary winding of said constant current transformer, short-circuiting means including a plurality of solenoid operated switches for separating said lamps into banks for the separate illumination thereof, a number of transformers equal to one less than the number of said solenoid operated switches having the primary windings connected in said series circuit, the secondaries of said transformers being connected respectively to said solenoids except for: said one solenoid, a number of switches equal to the number of transformers connected respectively to shunt the secondaries of said transformers, operating means for said switches, operating means for said one solenoid.

6. A control system for a plurality of banks of lamps comprising a source of substantially constant current electrical energy, means for connecting said lamps in a series circuit with said source, electrically operated short circuiting means between adjoining banks of lamps, and means for deriving electrical energy from said series circuit for energizing said electrically operated means.

7. A control system for a plurality of banks of lamps. comprising a source of substantially constant current electrical cnersyi means for con necting said lamps in a series circuit with. said source, electrically operated short circuiting means between adjoining banks of lamps, means for deriving electrical energy from said series circuit for energizing said electrically operated means, and means for remotely controlling said energizing means.

8. A control system for a plurality of banks of lamps comprising a source of substantially constant current electrical energy, circuit means for connecting all lamps in'series' to said source, short-circuiting means including an electrically operated switch between adjoining banks of lamps, a plurality of transformers having the primary windings serially connected in said banks of lamps, the secondary windings of said transformers being connected to the electrical operat ing means for said electrically operated switches, and means for shunting said secondary windings. 9. A control system for a plurality of lamps comprising a substantially constant current source of alternating current electrical energy, and means for connecting all lamps in series to said source in consecutive banks, said means comprising short-circuiting switches between adloining banks of lamps, electrical operating means for said short-circuiting switches, a plurality of transformers having the primary windings serially connected respectively in individual banks of lamps, and circuit means for connecting the secondary winding of each said transformers to the operating means of the short-circuiting switch between the bank of lamps in which the primary of that transformer is connected and the next successive bank, and shunting means for the secondary windings of said transformers.

10. A control system for a plurality of lamps comprising a source of alternating current electrical energy, means for deriving a substantially constant alternating current therefrom, means a for connecting all lamps in series in circuit with said constant current deriving means, a plurality of short-circuiting switches for separating said series lamp circuit into a number of banks of lamps equal to one more than the number or said short-circuiting switches, a plurality of individual electrical operating means equal to the number of said short-circuiting switches for the operation thereof, a plurality of transformers having the primary windings serially connected in individual banks of lamps, the secondary windings of said transformers being connected respectively to the electrical operating means of said shortcircuiting switches, a number of switches equal to the number of said transformers connected respectively in shunt with the secondary windings of said transformers, and remote electrical operating means for said last-named switches.

11. A sequential control system for a plurality of lamps comprising a source of alternating current, a constant current transformer having its primary terminals connected to said source, and means including transformers in circuit with said lamps for connecting all lamps in series to the secondary terminals of said constant current transformer in consecutive banks, said means comprising a plurality of short circuiting switches for separating said series lamp circuit into a number of banks equal to one more than the number of said short-circuiting switches, individual solenoid operating means for said shortcircuiting switches, a number of transformers equal to less than the number of said shortcircuiting switches, the primary winding of each of said transformers being serially connected respectively in the bank of lamps preceding the bank which that transformer is to supply the current to energize, the secondary winding of each transformer being connected respectively to the solenoid operating means for the short-circuiting switch between the bank in which that transformer is connected and the next successive bank, a number of remotely controlled switches equal to the number of transformers connected respectively in shunt with the secondary windings of said transformers, remote operating means for said 'last named switches, and means for 'ei'1er-' gizing the solenoid operating means for the bal-' ance of the short-circuiting switches not con nected to the secondary of one of said transformers.

12. A control system for a plurality of lamps operated from an alternating current constant current source of electrical energy including means for connecting said lamps in series to said constant current source, shunting means including a plurality of electrically operated switches for separating said lamps into consecutively energizable banks, the number of electrically operated'switches being equal to one less than the number of banks, a transformer foreach electrically operated switch, the secondary winding of each of said transformers being connected to energize one of said switches and the primary winding of each of said transformers being connected in circuit with the lamps in the bank preceding the switch to which its secondary is connected, a number of remotely operable switches equal to the number of said transformers connected respectively to short circuit the secondary windings thereof, and operating means for said remotely operable switches.

13. A control system for a plurality of lamps comprising a source of substantially constant current electrical energy, means for connecting said lamps in a series circuit with said source, shunting means including a plurality of electrically operated switches for separating said lamps into a plurality of banks equal to the number of said switches, and means for deriving electrical energy from said series circuit for energizing said electrically operated means.

14. A control system for a plurality of banks of lamps comprising a source of substantially constant current electrical energy, means for connecting said lamps in series in circuit with said source, shunting means including an electrically operated switch for each bank of lamps, a plurality of transformers having the primary windings connected in said series circuit, the secondary windings of said transformers being connected to said electrically operated switches, and selective means for shunting said secondary windmgs.

15. A control system for a plurality of banks of lamps comprising a substantially uniform source of alternating electrical current, means for connecting all lamps in series to said source, a plurality of short circuiting switches for separating said lamps into an equal number of banks, elec trical operating means for said short-circuiting switches, a number of transformers equal to the number of said banks having the primary windings thereof connected in series with said lamps, the secondary windings of said transformers being connected respectively to said electrical operating means, a number of switches equal to the number of transformers connected respectively to shunt the secondary windings of said transformers, and remote operating means for said last-named switches.

16. A selective control system for a plurality of lamps comprising a source of alternating current electrical energy, a constant current trans former having its primary terminals connected to said source, means for connecting said lamps in series to the secondary terminals of said constant current transformer in a plurality of independently connectable banks, a number of shunting switches equal to the number of said banks and connected respectively thereto, solenoid operating means for each said shunting switch, a number of transformers equal to less than the number of said banks having the primary windings thereof connected in said series circuit, the secondary windings of said transformers being connected to an equal number of said solenoid operating means, a number of switches equal to the number of said transformers connected re spectively to short-circuit the secondary windings of said transformers, solenoid operating meansjfor said last-named switches, selective remote control means for actuating the solenoid operating means for said last-named switches, and selective means for energizing the solenoid operating means for the balance of said shunting switches which are not connected to a transformer secondary winding.

17. A control system for a plurality of lamps operated from an alternatin current constant current source of electrical energy including means for connecting said lamps in series to said constant current source, shunting means including a plurality of electrically operated switches for separating said lamps into consecutively energizable banks, the number of electrically operated switches being equal to one less than the number of banks, a transformer for each electrically operated switch, the secondary winding of each of said transformers being connected to energize one of said switches and the primary winding of each of said transformers being connected in circuit with the lamps in the bank preceding the switch to which its secondary is connected, a number of remotely operable switches equal to the number of said transformers connected respectively to short circuit the secondary windings thereof, operating means for said remotely operable switches, and means for remotely controllin said energy deriving means.

18. A control system for a plurality of lamps operated from an alternating current constant current source of electrical energy including means for connecting said lamps in series to said constant current source in a plurality of selectively connectable banks, a number of electrically operated shunting and disconnecting switches equal to the number of said banks, each such switch being arranged to sequentially shunt a bank of lamps and then disconnect that bank from the main series circuit upon energization of the operating mechanism thereof and to sequentially reconnect the bank and then restore it to the main series circuit upon de-energization of the operating mechanism thereof, a transformer for each shunting and disconnecting switch, the secondary windings of said transformers being connected respectively to said shuntin and disconnecting switches for the operation thereof, the primary windings of said transformers being connected in the main series loop, a number of remotely operable switches equal to the number of transformers connected respectively to short circuit the secondary windings of said transformers, and selective operating means for said last-named switches.

19. A control system for a plurality of banks of lamps comprising a source of substantially constant current electrical energy, means for connecting said lamps in series in circuit with said source, shunting and disconnecting means including a plurality of electrically operated switches, each of said switches having one contact member to shunt a bank of lamps and at least one additional contact member to subsequently disconnect that bank from said series circuit upon energization of the switch operating means, said contact members operating in reverse order upon de-energization of the switch operatin means to reconnect the bank and subsequently restore it to said series circuit, a plurality of transformers having the primary windings connected in said series circuit, the secondary windings of said transformers being connected to said electrically operated switches, and selective means for shunting said secondary windings.

20. A control system for a plurality of lamps comprising a substantially constant current source of alternating current electrical energy, and means for connecting all the lamps in series to said source in consecutive banks, said means comprising a plurality of electrically operated switches, each of said switches having one contact member to shunt said series circuit and at least on additional contact member to subsequently disconnect the shunted portion of the series circuit from the remainder thereof upon energization of the switch operating means, said contact members operat ng in reverse order upon de-energization of the switch operatin means to reconnect the shunted portion of said series circuit and subsequently restore it to electrical series relationship with the remainder of the series circuit, a plurality of transformers having the primary windings serially connected in said banks of lamps, the secondary windings of said transformers being connected to the electrical operating means for said switches, and means for shunting said secondary windings.

PHILIP H. HOUSER.

No references cited. 

